Packages for single semiconductor elements or semiconductor devices may be wired packages or packages having solder bumps. Discrete semiconductor devices are mainly produced as wired packages and offered in so-called SMD (surface mounted device) packages. A SMD package is mounted directly onto the surface of a circuit board.
In a wired package, a semiconductor chip is applied or mounted to a metallic support (lead) or lead frame, wherein so-called bond wires (connecting wires) connect the contact pads (semiconductor contacts) of the semiconductor chip to the metallic support or lead frame. Thus, supports or lead frames in the application are connected to the associated conductive traces on the circuit board by means of solder in an electrically and/or thermally conducting way. The backside contact of the semiconductor chip here may also form an electrical and/or thermal contact to the lead frame. After connecting the semiconductor chip to the lead frame, the system is encapsulated by a sealing mass (mold), thus producing a package much larger than the actual chip.
Forming low cost chip scale packages is one of the significant challenges in packaging semiconductor devices.